Flexible airfoil for compressor

ABSTRACT

The inlet guide vanes for a turbine compressor are constructed of thin flexible material and mounted in a manner to be selectably formed into a desirable airfoil shape and camber angle by suitable control means.

United States Patent 11 1 Bartholomew 1 1 Mar. 27, 1973 [75] Inventor: Paul E. Bartholomew, Peoria, 111.

Y 154,110 11/1953 Australia ..4l5/161 I [73] Ass1gnee: Caterpillar Tractor Co., Peor1a,lll. 609,768 ll/I960 Canada "AIS/161 2 Filed: Jan 959,126 2/1957 Germany 4I5/I60 399,980 5/1941 Italy ..415/l60 {21] Appl. No.: 110,461

7 Primary Examiner-I-lenry F. Raduazo 52 us. c1 ..415/147, 415/160 Attorney-Fryer, Tiensvold, Feix; Phillips & Lempio [51] Int. Cl. ..F0ld 24/02, FOld 17/12 [58] Field of Search ..4l5/2l,19,146,147,148, ABSTRACT 415/149 130 The inlet guide vanes for a turbine compressor are 56 R f Ct d constructed of thin flexible material and mounted in a l 1 e erences I e manner to be selectably formed into a desirable airfoil UNITED STATES PATENTS shape and camber angle by suitable control means. 2,337,861 12 1943 Adomtchikm; ..415 147 2 Claims, 6 Drawing Figures IO 21 3o B FLEXIBLE'AIRFOIL FOR COMPRESSOR 8/1952 Bauger ..415/l60 FOREIGN PATENTS OR APPLICATIONS PATEF-HEBMAMHQM SHEET 2 [IF 2 INVENTOR PAUL E. BARTHO LOM EW +41 AT TORN EYS FLEXIBLE AIRFOIL FOR COMPRESSOR BACKGROUND OF THE INVENTION This invention relates to variable vanes for a stator and pertains more particularly to a vane formed of flexible material and deformable into the desired position for adjustment.

Turbine machines such as pumps, compressors and engines are required to operate efficiently over a wide range of fluid flow conditions. One way of improving efficiency is the provision of inlet guide vanes which control blade incidence angle.

The basic type of vanes used to produce variable blade incidence are adjustable stagger fixed camber, flapped, and articulated or hinged. The practical limit of vane exit flow deflection before choking of air flow occurs is about 25 for the fixed camber type of vane. This angle goes up to 35 for the hinged type. The air flow exits from these vanes at an angle less than that of the blades. This limited angle imposes a limit on the range over which such turbine machines may operate efficiently.

SUMMARY OF THE INVENTION It is therefore a primary object of the present invention to provide adjustable turbine vanes that provide for a wider range of efficient operation for turbine machinesv Another object of the present invention is to provide a simple and inexpensive guide vane assembly for turbine machines.

A further object of the present invention is to provide a guide vane assembly that can be adjusted to a larger camber angle than prior known devices before choking occurs.

In accordance with the present invention the vane for a turbine stator is constructed of thin flexible material and mounted so that it can be deflected to conform to the desired airfoil shape and angle of incidence.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a sectional view ofa portion ofa turbine engine incorporating the present invention.

FIG. 2 is a head on view of the vane of FIG. 1 showing part of the mounting and adjusting structure.

FIG. 3 is a top view of the vane in the nonadjusted position.

FIG. 4 is a head on view of the vane in its adjusted position.

FIG. 5 is a top view of the vane in its adjusted position.

FIG. 6 is an isometric view of a portion of the vane assembly.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS Referring now to the drawings and in particular to FIG. 1 there is illustrated a preferred embodiment of the present invention incorporated in an axial flow compressor assembly generally designated by the numeral 10 which may be incorporated for example in a gas turbine engine. The compressor assembly comprises generally a forward outer tubular housing structure 11 and a central core structure 12 supported therein by a plurality of radial struts l3 and forming an annular inlet opening 14. A nose portion 15 helps to guide the medium to be compressed into the inlet opening 14 which reduces gradually by smoothly curved walls to keep turbulence of a gaseous medium to be compressed at a minimum. A first stage compressor rotor 16 is rotatably supported by means of bearings 17 in a central housing 12 and is provided with suitable seal means 18. A rotor 16 carries a plurality of radially directed or disposed rotor blades 19 of suitable angle and configuration. The forward or inlet housing 11 is suitably supported from main housing 20 such as by means of a pair of flanges 21 and 22 and a support ring 23. Suitable means such as a plurality of bolts or pins 24 may be used for attaching the flanges 21 and 22 together.

An infinitely variable inlet guide vane assembly is disposed between inlet opening 14 and the rotor blades 19. The inlet guide vane assembly is comprised of a plurality of infinitely flexible variable camber vanes 25, each of which is supported in a substantially fixed manner at its leading edge and having suitable control means attached to the trailing edge for flexing the vane or deforming the vane into suitable shape and camber. Each of the vane members 25 is formed of a thin flexible material and shaped to be relatively narrow in the axial direction at the inner diameter of the vane assembly and to be wider or longer in the axial direction of the outer diameter. The vane assembly includes suitable support means such as for example an inner ring member 26 removably mounted in a suitable manner on central housing structure 12 and an outer support ring 27 attached such as by means of a flange 28 to the outer portion of the inlet housing 11. The outer trailing edge 25a of the vane member 25 is operatively coupled such as by rotatable pin 29 to a suitable control member such as an indexing ring preferably constructed of two parts 30 and 31 for ease of assembly. The indexing ring 30-31 may be supported in place such as by a centering bearing 32 carried by a support ring 33 and a pair of thrust bearings 34 and 35. The vane member 25 has its trailing edge preferably mounted off center from the central axis or rotative axis of the rotatable pin 29 as seen in FIGS. 2 and 3. The vane member 25 is also shown in FIGS. 2 and 3 in its normal unflexed or unadjusted position.

Rotation of the indexing ring 3031 about its central axis moves the trailing edge 25a of the vane member 25 out of alignment with the leading edge as shown in FIGS. 4 and 5 and forms an airfoil having the selected shape and camber. This rotational movement of the indexing ring 30-31 produces a greater deflection in the vane member 25 at the outer diameter than at the hub or inner diameter as can be seen in FIG. 5. Thus the lower trailing edge 25b of the vane member 25 is deformed to a lesser degree than the upper trailing edge 25a and likewise has a smaller camber angle. A suitable external actuating mechanism and linkage (not shown) may be suitably connected to pin 36 in FIG. 6 for actuating or rotating the index ring. This air foil construction has been found to produce a maximum air turning at the outer edge or tip without having to sacrifice overall compressor efficiency because the flexible airfoil minimizes pressure drop through the inlet guide vanes. The thinner overall profile of the vane permits a greater camber angle to be used before choking of the air path between the vanes occurs.

While the present invention has been shown and illustrated with respect to one illustrative form it will be obvious to those skilled in the art that various changes and modifications may be made without departing from the spiritand scope of the present invention as set forth in the appended claims.

I claim:

1. A variable camber guide vane assembly for a gas turbine engine comprising an outer ring assembly and a connected concentrically disposed smaller inner ring assembly arranged to form an annular air flow duct between said ring assemblies, a plurality of vanes disposed in said air flow duct, each of said vanes being constructed of unitary flat flexible material having a to distort the central portion and trailing edge of eachvane about a radial axis to uniformly change the camber of each vane to vary the flow through the annular duct.

2. The apparatus as defined in claim 1 wherein each of said vane members is formed to be wider at the outer diameter than at the inner diameter. 

1. A variable camber guide vane assembly for a gas turbine engine comprising an outer ring assembly and a connected concentrically disposed smaller inner ring assembly arranged to form an annular air flow duct between said ring assemblies, a plurality of vanes disposed in said air flow duct, each of said vanes being constructed of unitary flat flexible material having a leading edge portion and a trailing edge portion, anchor means at the top and bottom ends of each of said leading edge portion normally positioning said leading edge in a substantial radial plane within said air flow duct, adjusting means connected to one end only of said tRailing edge portion of each vane with the remaining end thereof being free of any connection thereto whereby adjustment of said means is operable to distort the central portion and trailing edge of each vane about a radial axis to uniformly change the camber of each vane to vary the flow through the annular duct.
 2. The apparatus as defined in claim 1 wherein each of said vane members is formed to be wider at the outer diameter than at the inner diameter. 